1. the weight of a liter of hydrogen (at 0 centigrade and 760 millimeters pressure);

The Collaborative International Dictionary of English v.0.48:

Crith \Crith\ (kr[i^]th), n. [Gr. kriqh` a barleycorn, a small weight.] (Chem.) The unit for estimating the weight of a["e]riform substances; -- the weight of a liter of hydrogen at 0[deg] centigrade, and with a tension of 76 centimeters of mercury. It is 0.0896 of a gram, or 1.38274 grains. [1913 Webster]WordNet (r) 3.0 (2006):

crith n 1: the weight of a liter of hydrogen (at 0 centigrade and 760 millimeters pressure)